Single-point, double-thread drive screw



April 14, 1931. J. A. ARENZ 1,801,186

SINGLE POINT, DOUBLE THREAD, DRIVE SCREW Filed Oct. 18, 1929 I x I II II9 19 avwauboz JOHN H m/Z abtcwfit V A Patented A r. 14, 1931 ,UNITEDSTATES JOHN A.

PATE T OFFICE ARENZ, OF MOUNT VERNON, NEW YORK, ASSIGNC DB TOINTEBHA'ITONAL SCREW 60., OF WILIINGTON, DELAWARE, A CORPORATION 01DELAWARE SINGLE-POINT, .DQUBLE-THBEA D DRIVE SCREW Application filedOctober 18, 1929, Serial 1W0. 400,875, and in Canada April 18, 1928.

This invention relates to screws and in particular to the type havingformed thereon a barbed double thread, each of the threads of whichterminate at the tip end of the screw 5 in a single point whereby thedriving qualities of the screw are increased and a screw is providedwhich can-either be screwed into the wood by-aiturning movement ordriven in with appli force.

The primary object of my invention 1s to provide a drive screw which canbe qulckly seated or"removed from it's seated position and the threadsof which run to the extreme shape of the threads being a particularfea-.

\ ture of my invention inasmuch as their shape provides a barb and ithas been found as the result of an exhaustive test made by one of thelargest engineering concerns in the world that my improved doublethreaded, single pointed barbed drive screw will normally resistapulling out force of from 100 to 300 percent greater than the resistanceoffered to apulling out force by single thread screws in present dayuse. 7 I Astill further object of my inventionis which facilitate itsintroduction into wood or other suitable work without the necessity ofthe aid of .a gimlet or hammer; the screws being insertible at a muchgreater'speed and with a minimum of power. My improved features alsoincrease the holding power of the screws and thereby ensure safety and"permanent connection of the parts secured by the screws. The barbthread which terminates in a single piercing point as employed inconnection with my improved screw as I sists in placing the screw withthe least possi- I ble damage to thefibers of the wood by '50theoretically lifting the wood on the screws thread barbed, singlepointed drive screw to provide a screw having features thereon whichterminate in a single point 10 at the under its fibrous formationwithout losing or destroyin its holding possibilities.

With t e foregoing and other objects in view, which will a pear as thedescription proceeds, the inven ion resides in the combination andarrangement of parts and in the details of construction hereinafterdescribed and claimed, it being understood that changes in the preciseembodiment of theinvention hereby disclosed may be made with in thescope of what is claimed without departing from the spirit of theinvention.

In the drawings: a p

Figure 1 is a view in elevation of a double which constitutes myinvention.

Figure 2is a greatly enlarged view in elevation of the lower section ofa screw as illustrated in Figure 1 having an intermediate portionthereof shown in section to .illustrate the shape of the thread whichprovides the driving barb.

Figure 3 is an enlarged view looking at the tip end of the screwillustrated in Figure 2.

Figure 4 is a fragmentary section showing how the fibers of the .woodare separated and are crowded into the barb of my improved screw so thata pull out force applied to the screw is effectively resisted, and

Figure 5 is a view of the tip end of the screw illustrated in Figure 2,the "view being taken at right angles through said figure.

Referring now specifically to the drawings in which like referencecharacters denote like parts throughout, and in particular to Figure 1'in which my single pointed, double threaded barbed drive screw isillustrated, having a cylindrical body portion 5 and any type of head 6turned thereon, this head, of course, being provided with a screw driverslot 7 afterthe usual manner whereby the screw may be turned into theholding material. A portion 8 of the body of the screw is provided withthe double threads 8,and 9' lower tip end of the screw body 5. Thesescrew threads 8 and 9 are interspaced with relation to each other sothat the travel of the screw when turned into or out of position in theholding material is much more ting edges 12 and 13. The cutting edge 12'in Figure 3 marking the termination of the thread 8 while the cuttingedge 13 marks the termination of the thread 9. These cutting edges 12and 13 converge to form the Single point 10 which constitutes the piersing point o-fthe screw. These cutters prepare the way' for the twothreads and make unnecessary the use of a hammer or other with the typeof screws previously implement to force the screw into the materialbefore it can be started to actually take hold of the material. However,in quick work where the saving of time is very essential, the screw maybe driven into the work by a blow with a hammer striking the head 6. Ateach blow the threads, by cut it ting into the wood fiber, will causethe screw to rotate under the force of the blow and make a clean threadcut-upon the inner wall of the opening formed by the screw withoutbreaking down the wood fiber asis the case produced and now commonlyused.

These cutting edges 12 and 13 form an important part of m invention andparticularly in View of the 1 1 which, asjbefore descri ed, is extremelyefiective in providing a proper start for the screw and also providingfor its straight travel through the material, it being of courseunderstood that the point '14 is in actual alignment with the body ofthe screw 5 and the balanced type or thread prevents the screw. frombeing inserted in a direction.

' other than that desired. These cutting edges 12 and 13 in addition,out under the wood fibers and keep drawing the screw into'the woodrapidly by reason ofr' the alternate threads 8 and 9, that is to say,the distance of travel is increased and the screw driven always to theextent of two threads -,at a time due to entrance of both threadssimultaneously whereas, in known double thread screws, this feature isnot in evidence hecause the point constructiondoes not bring the doublethreads into action at onceand for that reason their efiicacyis lost andnever properly regained and this has been proven out in comparativetests which have clearly shown that a indouble or even quadruple threadscrews, there is little or no gain in speed unless thethreads arerespectively in fact that they are tapered to provide the singlepiercing pointaeomee action from the start and together continuously. Incuttin the threads 8 and 9, it is preferable that a arbed ed 6 15 heprovided thereon, as illustrated in igure 4 so that this barbed edgewill engage beneath thefibers of the material in whichthe screw isdriven or rather into the material throu h which the screw draws itself.Both of t e threads are formed in the same manner, and it is believedthat a description of one will sufficef The thread of course, is ctormedby cutting its periphery 16 at an an Ie, the lower peripheral edge 17 ofeach t read terminating at the inner peripheral corner 18 of theshoulder 19 which, due to the taper of the thread, is provided at itsupper edge. The shar er the angle of taper of the thread, the quic erthe screw will enter the wood, because the pitch angle will necessarilybe greater. The shelf 19 or shoulder is cut downwardly or at an angle tothe outer periphery 16 ofthe thread of less than 90 degrees andpreferably at an acute angle as illustrated in Fi ure 4 to rovide thebarb 15, which, as be ore state will effectively separate the fibers andwill cause them to be seated on the topshelf or shoulder of each of thethreads with the result that the screw will rapidl .work its Way intothe material and its hold i muchgreater than has heretofore been thecase, in the employment of the well known type of screw.

If desired, of course, the shelf or shoulder 19 may be cut horizontallywithput sacrificmg any of the driving qualities of the screw and it isto be understood that while I have shown thebarbed type of thread, I amnot to be limited to this employ any desire angle of shoulder 19 in'connection with my single pointed, double threaded screw;

It is to be understood therefore,.that the H salient features of'myinvention are the prong power in the material will be (particular formbut may vision of a double-thread, the upper edges of which are barbedto provide a fiber wedging surface whichdrawsthe screw "rapidly into thematerial in which it is to be held and also the termination of thedouble thread in a mination of cutting edges which are tapered towardsaid point and which facilitates the entrance of'thescrew into the woodand immediately starts the drivingjaction of the invention with somedegree of particularity,

I realize that in practice various-alterations therein may be madewithout departing from the spirit of the invention or" the scope of theappended claims.

115 single piercing point which marks the ter- 1 What I claim is 1. Adrive element comprising a stem and tapered point having a plurality ofthreads of the barbed type spirally extending to the extreme tip of thetapered portion, the ends of said spiral being merged to form a sharppoint and forming oppositely positioned cuttin edges extending from saidpoint to initially open the work to the path of the screw in penetratingoperations, the threads having their outer face inclined away from thepoint throughout their length toward the shank of the stem, the threadsbeing c0ntinuous from the tip of the point to the shank of the stem.

2. As a new article of manufacture a drive element comprising a stemhaving a driving end and a portion gradually tapering toward one end andhaving formed thereon a plurality of threads at a pitch of approxi-'mately 45 degrees spirally extending-from the extreme tip of the stemtoward the opposite end of the stem, the forward ends of said spiralsbeing merged to form a sharp point, and forming oppositely positionedcutting edges extending from said point to initially open the work, saidthreads having their outer leading faces inclining from the ridge of thethread to the body of the stem toward the point of the stem and awayfrom the driving end of the stem, whereby to feed and revolve the driveelement into the work when it is subjected to a blow on the driving endthereof. a

In testimony whereof, I have signed my name to this specification this17th day of October, 1929.

JOHN A. ARENZ. [L. s.]

